//
//  StatusPictureView.swift
//  SinaWeibo
//
//  Created by 周小伟 on 16/8/25.
//  Copyright © 2016年 周小伟. All rights reserved.
//

import UIKit
import SnapKit
import SDWebImage

private let PictureCellId = "PictureCellId"
private let PictureCellMargin:CGFloat = 5

class StatusPictureView: UICollectionView {
    
    var imageURLs:[NSURL]?{
        didSet{
            reloadData()
            let viewSize = self.calceViewSize()
            self.snp_updateConstraints { (make) in
                make.width.equalTo(viewSize.width)
                make.height.equalTo(viewSize.height)
            }
            
            testLabel.text = "\(imageURLs?.count ?? 0)"
        }
    }

    private func calceViewSize()->CGSize{
        let colum:CGFloat = 3.0000000000001
        let maxWidth = screenW - 2 * StatusCellMargin
        
        let itemWidth = (maxWidth - 2 * PictureCellMargin)/colum
        let layout = self.collectionViewLayout as! UICollectionViewFlowLayout
        layout.itemSize = CGSizeMake(itemWidth, itemWidth)
        
        let imageCount = imageURLs?.count ?? 0
        if imageCount == 0{
            return CGSizeZero
        }
        
        //单张图片
        if imageCount == 1{
            let key = imageURLs?.last?.absoluteString
            print(key)
            let image = SDImageCache.sharedImageCache().imageFromDiskCacheForKey(key!)
            let imageSize = image.size
            layout.itemSize = imageSize
            return imageSize
        }
        
        if imageCount == 4{
            let w = itemWidth * 2 + PictureCellMargin
            return CGSize(width: w, height: w)
        }
        
        let row = CGFloat((imageCount - 1)/3 + 1)
        let w = maxWidth
        let h = row * itemWidth + (row - 1) * PictureCellMargin
        return CGSizeMake(w, h)
        
    }
    
    init(){
        let layout = UICollectionViewFlowLayout()
        layout.minimumLineSpacing = PictureCellMargin
        layout.minimumInteritemSpacing = PictureCellMargin
        super.init(frame: CGRectZero, collectionViewLayout: layout)
        registerClass(PictureCell.self, forCellWithReuseIdentifier: PictureCellId)
        dataSource = self
        setupUI()
    }
    
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    private func setupUI(){
        backgroundColor = UIColor.randomColor()
        addSubview(testLabel)
        
        testLabel.snp_makeConstraints { (make) in
            make.center.equalTo(self.snp_center)
        }
    }
    /*
    // Only override drawRect: if you perform custom drawing.
    // An empty implementation adversely affects performance during animation.
    override func drawRect(rect: CGRect) {
        // Drawing code
    }
    */

    private lazy var testLabel:UILabel = {
        let l = UILabel()
        l.font = UIFont.systemFontOfSize(25)
        l.textColor = UIColor.redColor()
        l.sizeToFit()
        return l
    }()
}

extension StatusPictureView:UICollectionViewDataSource{
    func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return imageURLs?.count ?? 0
    }
    
    func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCellWithReuseIdentifier(PictureCellId, forIndexPath: indexPath) as! PictureCell
        cell.url = imageURLs![indexPath.item]
        return cell
    }
}

class PictureCell: UICollectionViewCell {
    var url:NSURL?{
        didSet{
            imageView.sd_setImageWithURL(url,placeholderImage:nil)
        }
    }
    
    override init(frame: CGRect) {
        super.init(frame: frame)
        setupUI()
    }
    
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:)has not been implemented")
    }
    
    private func setupUI(){
        contentView.addSubview(imageView)
        imageView.snp_makeConstraints { (make) in
            make.edges.equalTo(contentView.snp_edges)
        }
    }
        private lazy var imageView:UIImageView = {
           let iv = UIImageView()
            iv.contentMode = UIViewContentMode.ScaleAspectFill
            
            iv.clipsToBounds = true
            return iv
        }()
}
